Is there a way to rerun analysis without doing a commit? For example, if I add a code coverage exclusion pattern under Analysis Scope and want to test if it works, I would like to rerun the analysis without doing a commit or involving any external tool.

If you think about a CI service like TravisCI or Jenkins, which is used to trigger scanner, then answer is no. Analysis configuration is applied only when re-analysing sources, so by pushing a new commit or by restarting the scanner job.